The present invention relates to a loader for insertion of bars in automatic lathes.
There are known loaders of bars into lathes comprising a pusher pushing axially a bar along running guides to introduce it progressively into the lathe spindle. A problem with said loaders is the space occupied. Indeed, the length of the loader must be theoretically equal to the sum of the length of the bar to be loaded plus the length of the pusher. The pusher must then be sufficiently long to push the bar completely into the lathe spindle.
To seek to reduce the space occupied, in the known art there have peen proposed loaders having two pushers, one acting along the first part of the thrust path and one acting along the second part. In this manner the first pusher can be provided relatively short since it does not have to enter the spindle and the second pusher longer since it does not need to follow the bar except when the latter is already partially inside the spindle. The need to provide two separate kinematic mechanisms for movement of the two pushers involves however construction complications and relatively high costs.
To reduce the costs and complications there have also been proposed loaders in which the two pushers use the same kinematic mechanism, selective constraint means permitting choice of which pusher is to be moved each time. The complication of said systems is however high.
There have also been proposed loaders in which the longer pusher arranges itself ahead of the short pusher. The constraint means between the pushers are however always outside the space occupied by the pusher and interfere with the bar guides, causing construction complications. The pusher with the extension is not assimilable as to behaviour with an individual pusher but produces vibrations and operating defects.
The purpose of the present invention is to obviate the above mentioned shortcomings by supplying bar loaders in which the pusher is provided in two separable parts with the two parts behaving upon connection as a single pusher which passes without problems into the bar guides.